I updated the Autotools build so that it should now correctly build
js_embed in a form that's executable on the build machine. It is not in
master yet but it is on my cross-compilation branch here:
https://github.com/acozzette/protobuf/tree/cross-compilation Maxx, when you
have a chance you could you try building on that branch and let me know if
it works?

On Tue, Jan 3, 2017 at 11:53 AM, Adam Cozzette <[email protected]> wrote:

> I hadn't thought about the cross-compilation use case for this. It seems
> to me that there are a few different ways to solve this:
> 1. Just check well_known_types_embed.cc into Git and we can update it
> manually when necessary. This is probably the easiest solution but is a
> little bit messy since it requires us to check in another build artifact.
> 2. Fix the Autotools build to do the cross-compilation properly on its
> own. For this we would probably want to use the AX_PROG_CXX_FOR_BUILD macro
> from here
> <https://www.gnu.org/software/autoconf-archive/ax_prog_cxx_for_build.html> as
> a way of finding the right C++ compiler to use for building binaries that
> need to run as part of the build.
> 3. Rely on Bazel for cross-compilation since it is pretty good at handling
> this automatically: https://bazel.build/versions/master/docs/
> bazel-user-manual.html#configurations
> 4. Rewrite js/embed.cc as a Python or Perl or shell script so that it
> doesn't require compilation. The problem with this is that it would add
> another dependency to the build and might make it less portable (e.g. for
> Windows).
>
> Let me try using the AX_PROG_CXX_FOR_BUILD macro and see if that will work.
>
> On Tue, Jan 3, 2017 at 11:12 AM, 'Feng Xiao' via Protocol Buffers <
> [email protected]> wrote:
>
>> +acozzette
>>
>> The js_embed binary was added very recently. The cross-build support for
>> that binary is missing at the moment. As a temporary solution, you can use
>> this version of protobuf (which doesn't have the js_embed binary):
>> https://github.com/google/protobuf/releases/tag/v3.1.0
>>
>>
>> On Wed, Dec 28, 2016 at 11:57 PM, Maxx Becker <[email protected]>
>> wrote:
>>
>>> I'm a newbie, but I have successfully built the protocol buffers sources
>>> (version 3.1.0) on Ubuntu 14.04 x86_64 and installed, as per
>>> https://github.com/google/protobuf/blob/master/src/README.md
>>> I am now attempting to cross-compile to an ARM target, using the
>>> cross-compiling info from the README above and the following as references:
>>> https://groups.google.com/forum/#!topic/protobuf/ZWuTzg-N0E0
>>> After running 'make clean' and re-configuring to use the
>>> arm-linux-gnueabihf compilers and the previously installed x64 protoc, I
>>> encounter a error that indicates it is attempting to use the js_embed
>>> binary built for ARM in the process.
>>> Relevant info as follows:
>>>
>>> $ which protoc js_embed
>>> /usr/bin/protoc
>>> /usr/bin/js_embed
>>>
>>> $ file /usr/bin/protoc /usr/bin/js_embed
>>> /usr/bin/protoc:   ELF 64-bit LSB  executable, x86-64, version 1 (SYSV),
>>> dynamically linked (uses shared libs), for GNU/Linux 2.6.24,
>>> BuildID[sha1]=637edeade5ad13f462551a45ae1285e55a2a1f3c, not stripped
>>> /usr/bin/js_embed: ELF 64-bit LSB  executable, x86-64, version 1 (SYSV),
>>> dynamically linked (uses shared libs), for GNU/Linux 2.6.24,
>>> BuildID[sha1]=e49255de4711facf660f838ad7bad9b01525cf12, not stripped
>>>
>>> $ arm-linux-gnueabihf-gcc --version
>>> arm-linux-gnueabihf-gcc (Ubuntu/Linaro 4.8.4-2ubuntu1~14.04.1) 4.8.4
>>> $ arm-linux-gnueabihf-g++ --version
>>> arm-linux-gnueabihf-g++ (Ubuntu/Linaro 4.8.4-2ubuntu1~14.04.1) 4.8.4
>>>
>>> $ g++ --version
>>> g++ (Ubuntu 4.8.4-2ubuntu1~14.04.3) 4.8.4
>>> $ gcc --version
>>> gcc (Ubuntu 4.8.4-2ubuntu1~14.04.3) 4.8.4
>>>
>>> $ make clean
>>> $ ./configure --host=arm-linux-gnueabihf CC=arm-linux-gnueabihf-gcc
>>> CXX=arm-linux-gnueabihf-g++ --with-protoc=/usr/bin/protoc
>>> --prefix=/programs/protobuf
>>> (Can post output if desired)
>>>
>>> $ make
>>> make  all-recursive
>>> make[1]: Entering directory `/storage/tools/protobuf'
>>> Making all in .
>>> make[2]: Entering directory `/storage/tools/protobuf'
>>> make[2]: Leaving directory `/storage/tools/protobuf'
>>> Making all in src
>>> make[2]: Entering directory `/storage/tools/protobuf/src'
>>> /usr/bin/protoc -I. --cpp_out=. google/protobuf/any_test.proto
>>> google/protobuf/compiler/cpp/cpp_test_bad_identifiers.proto
>>> google/protobuf/map_lite_unittest.proto 
>>> google/protobuf/map_proto2_unittest.proto
>>> google/protobuf/map_unittest.proto google/protobuf/unittest_arena.proto
>>> google/protobuf/unittest_custom_options.proto
>>> google/protobuf/unittest_drop_unknown_fields.proto
>>> google/protobuf/unittest_embed_optimize_for.proto
>>> google/protobuf/unittest_empty.proto 
>>> google/protobuf/unittest_enormous_descriptor.proto
>>> google/protobuf/unittest_import_lite.proto
>>> google/protobuf/unittest_import.proto 
>>> google/protobuf/unittest_import_public_lite.proto
>>> google/protobuf/unittest_import_public.proto
>>> google/protobuf/unittest_lite_imports_nonlite.proto
>>> google/protobuf/unittest_lite.proto google/protobuf/unittest_mset.proto
>>> google/protobuf/unittest_mset_wire_format.proto
>>> google/protobuf/unittest_no_arena_lite.proto
>>> google/protobuf/unittest_no_arena_import.proto
>>> google/protobuf/unittest_no_arena.proto 
>>> google/protobuf/unittest_no_field_presence.proto
>>> google/protobuf/unittest_no_generic_services.proto
>>> google/protobuf/unittest_optimize_for.proto
>>> google/protobuf/unittest_preserve_unknown_enum2.proto
>>> google/protobuf/unittest_preserve_unknown_enum.proto
>>> google/protobuf/unittest.proto google/protobuf/unittest_proto3_arena.proto
>>> google/protobuf/unittest_proto3_arena_lite.proto
>>> google/protobuf/unittest_proto3_lite.proto
>>> google/protobuf/unittest_well_known_types.proto
>>> google/protobuf/util/internal/testdata/anys.proto
>>> google/protobuf/util/internal/testdata/books.proto
>>> google/protobuf/util/internal/testdata/default_value.proto
>>> google/protobuf/util/internal/testdata/default_value_test.proto
>>> google/protobuf/util/internal/testdata/field_mask.proto
>>> google/protobuf/util/internal/testdata/maps.proto
>>> google/protobuf/util/internal/testdata/oneofs.proto
>>> google/protobuf/util/internal/testdata/proto3.proto
>>> google/protobuf/util/internal/testdata/struct.proto
>>> google/protobuf/util/internal/testdata/timestamp_duration.proto
>>> google/protobuf/util/internal/testdata/wrappers.proto
>>> google/protobuf/util/json_format_proto3.proto
>>> google/protobuf/util/message_differencer_unittest.proto
>>> google/protobuf/compiler/cpp/cpp_test_large_enum_value.proto
>>> touch unittest_proto_middleman
>>> depbase=`echo google/protobuf/compiler/js/embed.o | sed
>>> 's|[^/]*$|.deps/&|;s|\.o$||'`;\
>>> arm-linux-gnueabihf-g++ -std=c++11 -DHAVE_CONFIG_H -I. -I..    -pthread
>>> -DHAVE_PTHREAD=1  -Wall -Wno-sign-compare -O2 -g -DNDEBUG -MT
>>> google/protobuf/compiler/js/embed.o -MD -MP -MF $depbase.Tpo -c -o
>>> google/protobuf/compiler/js/embed.o google/protobuf/compiler/js/embed.cc
>>> &&\
>>> mv -f $depbase.Tpo $depbase.Po
>>> /bin/bash ../libtool  --tag=CXX   --mode=link arm-linux-gnueabihf-g++
>>> -std=c++11 -pthread -DHAVE_PTHREAD=1  -Wall -Wno-sign-compare -O2 -g
>>> -DNDEBUG -pthread  -o js_embed google/protobuf/compiler/js/embed.o
>>> libtool: link: arm-linux-gnueabihf-g++ -std=c++11 -pthread
>>> -DHAVE_PTHREAD=1 -Wall -Wno-sign-compare -O2 -g -DNDEBUG -pthread -o
>>> js_embed google/protobuf/compiler/js/embed.o  -pthread
>>> oldpwd=`pwd` && cd . && \
>>> $oldpwd/js_embed google/protobuf/compiler/js/well_known_types/any.js
>>> google/protobuf/compiler/js/well_known_types/struct.js
>>> google/protobuf/compiler/js/well_known_types/timestamp.js >
>>> $oldpwd/google/protobuf/compiler/js/well_known_types_embed.cc
>>> */bin/bash: line 1: /tools/protobuf/src/js_embed: cannot execute binary
>>> file: Exec format error*
>>> make[2]: *** [google/protobuf/compiler/js/well_known_types_embed.cc]
>>> Error 126
>>> make[2]: Leaving directory `/storage/tools/protobuf/src'
>>> make[1]: *** [all-recursive] Error 1
>>> make[1]: Leaving directory `/storage/tools/protobuf'
>>> make: *** [all] Error 2
>>>
>>> $ file src/js_embed
>>> src/js_embed: ELF 32-bit LSB  executable, ARM, EABI5 version 1 (SYSV),
>>> dynamically linked (uses shared libs), for GNU/Linux 2.6.32,
>>> BuildID[sha1]=74fb68528ae9db46637e1570eeda640ae9f318f1, not stripped
>>>
>>> It's unclear how I can direct the compilation process to use the
>>> js_embed binary in /usr/bin, instead of the js_embed binary it builds for
>>> ARM. Any help or direction is appreciated. Thanks!
>>>
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>>
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>
>

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